In Bergeron et al U.S. Pat. No. 5,233,772, issued Aug. 10, 1993, entitled Multi-Message Sign Paul E. Bergeron, the named inventor herein, and David L. Wood disclosed a new and novel rotating sign. Specifically, there was disclosed a driving butterfly cam in combination with a triangular cam follower attached to side-by-side rotating triangular sign elements. In short, this design discloses a highly successful rotating three-message display. Simply stated by having the side-by-side triangular sign elements rotate together, three sequential messages are repeatedly displayed.
It has been known to place illumination centrally of each side-by-side triangular sign element. However, practical signs of this design have not yet achieved full commercial acceptability. Examining carefully the design of Bergeron et al. U.S. Pat. No. 5,233,772, issued Aug. 10, 1993, entitled Multi-Message Sign, it has been found that this design is a perfect place for the placement of an internal light source, such as a central fluorescent tube, in each of the side-by-side triangular sign elements. The portions of the drive cams and journals required for the rotation of the sign elements naturally fit around internal light source, such as a stationary fluorescent tube. The exact parameters of how an internal light source to this design of sign were under development at the time of the filing of the Provisional Patent Application. What follows is a record of the development of this sign as of the date of filing of the Provisional Patent Application in the United States.
Each of the three messages of such signs is contained on sign strips. Where the sign strips are back illuminated, it is required that the message carrying sign strips be translucent. The translucent message carrying sign strips have to be held to the individual sides of the three-element rotating strips. For each of the three messages displayed, a set of translucent message strips is installed across the sign face with one strip carrying the sequential information on each sign element. There is herein developed the use of translucent and opposed U-shaped transparent holders extending the length of the sign elements at the edges of the three transparent display surfaces of the sign elements. These U-shaped transparent fittings oppose one another. When a translucent sign strip is inserted between the opposed translucent U-shaped edges, it is captured and held flat to the mating flat surface of the rotating three sided sign element.
It is important to understand why the translucent message carrying strips must be held by translucent opposed U-shaped elements. The translucent strips must be back illuminated to their edges. If the edges are blacked out or otherwise obscured, both a visual distraction and some obscuration of the message will occur. Accordingly, by making the retaining and opposed U-shaped members translucent, convenient insertion and withdrawal of these strips can occur with illumination extending to the edge of the strips extending across the message display surface of the sign.
In testing illumination of this three-dimensional sign, two problems were discovered, which problems are not disclosed and set forth in the prior art. As it is well understood that discovery of a problem can be combined with the solution to the problem, it will be understood that invention is claimed in recognizing the problem as well as solving the problem once known. No reference to the existence of these problems was found in the prior art.
When three-element rotating sign elements were centrally illuminated by illumination extending centrally of the rotating three-sided element, it was discovered that the centrally extending illumination causes the central portion of the translucent message carrying strip to be brightly illuminated. This is to be contrasted with those portions of the translucent message carrying strip that are at the edges of each display surface of the rotating triangular sign element. These edge portions of the back illuminated translucent message carrying strips are more remote from the internal light source. These edge portions appear noticeably darker. This uneven illumination is distracting and renders an unsatisfactory appearance where the sign is illuminated by a centrally extending source of illumination.
Given the uneven illumination, it is believed the reason for the uneven illumination to be the so-called xe2x80x9cinverse square lawxe2x80x9d related to light and other radiation. Simply stated, the intensity of light varies with the inverse square of the distance of the light source to the illuminated surface. For a small advertising sign utilized at indoor locations, thepreferred internal light source is a fluorescent tube is xc2xc inch in diameter. The rotating triangular sign elements are 2 inches on each side. When laid flat over the display surface of the rotating triangular sign element, the central portion of the back illuminated translucent message carrying sign strip is xc2xd inch away from the central fluorescent tube. The peripheral portions of the back illuminated strip are 1 inch away from the central fluorescent tube. The intensity of the illumination at the center of the back illuminated translucent message carrying strips is at least four times the intensity of the illumination at the strip edges. It will be appreciated that as the scale of the sign changes, the above dimension can proportionally change when the dimensions of the sign change.
A discovery has also been made related to the translucent and opposed U-shaped holders. It was found that the translucent and opposed U-shaped holders can radiate light to the viewer. The translucent and opposed U-shaped strip retaining elements form a bright boarder as the three message sign either displays its sequential messages or changes its sequential messages. As all of the elements of a multi-element three message sign rotate together, the brightly illuminated strips between the individual message strips of the sign likewise move together across the field of view of the sign message. The result is unbelievably distracting, rendering the rotating sign message display commercially unacceptable.
Having identified a bright boarder as a problem, the natural solution would be to render the translucent and opposed U-shaped holders of the individual sign message strips opaque. This will not result in the desired visual effect. Illumination is required to the edge of such strips. Accordingly, opaque opposed U-shaped holders at the edge of such sign elements would obscure portions of the back illuminated translucent message carrying sign strips. Such opaque holders cannot be used.
As a result of the recognition and study of these problems, there is developed herein a sign strip display that does away with both of these problems.
Between the filing of the Provisional Patent Application referenced above, and the filing of this Non-Provisional Patent Application, two remain problems that relate to the placement of central fluorescent tubes were found.
The first problem relates to the holding of the triangular sign elements themselves. It was found that bracing of display surfaces at the ends of the triangular sign elements can cause shadowing of the display surfaces at the ends of the triangular sign elements. Specifically, at the top and bottom of each flat display surface, shadowing occurs where the vane is mounted for rotation. These dark patches are distracting and interfere with the effectiveness of the message being displayed.
The second problem relates to an internal light source within the sign elements. Specifically, from time to time, internal light sources, such as fluorescent bulbs, fail. Each time a light source fails, it needs to be replaced at minimum cost without requiring either substantial sign disassembly or alternatively the presence of especially trained personnel to make the replacement. Accordingly, a new way of mount both the internal light source, such as the fluorescent bulb, and the rotating vane was required for facilitating both vane removal and internal light source replacement.
A three-message sign having internal light source has an array of side-by-side triangular sign elements. Each of the triangular sign elements has three transparent display surfaces with three apices joining the three transparent display surfaces into the triangular sign element. The transparent display surfaces permit the array to display a discrete message when the array of triangular sign elements is simultaneously rotated to present the display surfaces for a single message. Each of the side-by-side triangular sign elements has a internal light source extending from at least one end of the triangular sign element across the transparent display surfaces of the triangular sign element. Transparent and opposed U-shaped holders are placed along edges of the transparent display surfaces, each transparent and opposed U-shaped element defining an indentation for trapping the edges of translucent message display strips. The translucent display strips permit light from the internal light source to back illuminate the translucent message display strips. An opaque barrier is placed at the pieces of the triangular sign elements for blocking light passage through the transparent and opposed U-shaped holders. This opaque barrier prevents light passing between the edges of the translucent message display strips through the apices of the triangular sign elements. This prevents a strip of light when either static display or rotation of the side-by-side triangular sign elements occurs. Translucent message-carrying strips are mounted to the display surfaces between the transparent and opposed U-shaped holders. These translucent message-carrying strips are wider than an interval between the transparent and opposed U-shaped holders. This width causes the translucent message carrying strips to arcuately bow away from a flat disposition to an arcuate disposition concave with respect to the internal light source to provide apparent even illumination to the translucent message carrying strip.
As of the filing of this Non-Provisional Patent Application, two additional features have been added. First, all vanes are held between their respective flat transparent display surfaces by bisecting planar holders. These bisecting planar holders do not shade the respective flat transparent display surfaces and enable the translucent message display surfaces to be evenly illuminated at the rotating sign element ends. Secondly, a flexible U-shaped support is provided to at least one end of each rotating sign element. The xe2x80x9cUxe2x80x9d of the U-shaped support opens outwardly from the displaying surface of the sign. Utilizing a standard mounting fixture, both the triangular rotating element and the internal light source may be rotated out of engagement with and detached from the sign. Thereafter, a new internal light source, such as a fluorescent bulb can be threaded to the triangular rotating sign element, and the triangular rotating sign element rotated back into engagement with and attached to the sign.